Good oil is not cheap, but a good value. I have used diesels up north in cold winter weather for years, and in all of my diesel trucks, cars, tractors I use Amsoil products. Yes, it costs a little more, but the peace of mind for excellent internal protection and longevity of our expensive machinery is well worth the few extra dollars to get the best oil. Engine oil not only lubricates, but is the main way to transfer heat from the cylinders to the coolant, and synthetic oils provide the best performance. Winters are tough on engines and Amsoil base stock flows over a wide range of temps, including arctic temps. Heating the coolant when cold is excellent to help crank over the engine. I have found that oil lubrication additives can provide carryover lube until oil flows throughout the engine and are a cheap insurance cost for reliability, and can even provide fuel savings.
Bottom line - engine oil is not where to scrimp IMO.
Bottom line - engine oil is not where to scrimp IMO.